Output online prediction to external device

About the GUI application to design signal processing pipelines
Post Reply
techn
Posts: 2
Joined: Wed May 11, 2016 11:55 am

Output online prediction to external device

Post by techn »

Hi,
I am currently trying to develop a BCI using an Emotiv Epoc and a Novint falcon haptic device as the output device. Using Openvibe I can receive the emotiv data fine and I will test out the motor imagery examples but I would like to output online classification predictions to the haptic device.

I have seen the vrpn tutorial for application output, though to be honest I found it tricky as I am not familiar with c++. The output device uses Chai3D with key presses used to move its arm left or right. When this is running I can send a key press from matlab to Chai3D So from within Openvibe how would I go about sending a command or key press to another application based on each online prediction?

Is it easier to send this directly to Chai3D (if possible) or perhaps send the prediction to matlab and then onto Chai3D (if the vrpn stuff works with matlab)?

Thank you

techn
Posts: 2
Joined: Wed May 11, 2016 11:55 am

Re: Output online prediction to external device

Post by techn »

Ok so I've got the openvibe to vrpn tutorial example working. I've also tried hooking up the buton and analog boxes to my online scenario.

Connecting the classifier 'labels [stimulations]' output to a button vrpn box does not print anything but I suspect that's the C++ code. It is at least conencted to the vrpn.
Is this the output that would give a single prediction value?

On the other hand connecting the classifiers other outputs, probability values or hyperplane distances, to an analog vrpn box gives a constant stream of values that I can't imagine using.

Is there a way to output a single classification value computed after the online stimulus presentation?
I basically just want to externally compute, if the prediction is this... send command to move the arm.

The C++ code completely baffles me, so if the prediction could be sent to matlab that would be preferable.

jtlindgren
Posts: 778
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Output online prediction to external device

Post by jtlindgren »

Hi Techn, sorry for the late reply! You can send stimulations to Matlab using the Matlab scripting box, or perhaps LabStreamingLayer. To send stimulations out from VRPN, you need to use the VRPN Button Client. There's several scenarios in OpenViBE (including the basic SSVEP demo - not the mind shooter) that do this, the corresponding reception coded on the C++ client side. In

/applications/examples/openvibe-to-vrpn/

You will see a simple C++ client to receive stimulations (button presses) from OV.

In general, you can see different communication ways described here,

http://openvibe.inria.fr/overview-sendi ... -openvibe/

Happy hacking,
Jussi

Post Reply